Partially crimped stent

ABSTRACT

A crimping method that crimps a stent over multiple catheters. The method includes differentially crimping a stent on certain portions of a balloon catheter so that a second catheter can be threaded through the uncrimped portion of the stent and exit through the links of a conventional stent design or through a specific hole in the stent designed for a branched vessel.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application is a continuation of International PCTApplication No. PCT/US2009/058505 filed Sep. 25, 2009 which claims thebenefit of U.S. Provisional Patent Application No. 61/194,346 filed Sep.25, 2008, the entire contents of each of which are incorporated hereinby reference.

The present application is related to U.S. patent application Ser. No.13/071,251, filed the same day as the present application. The presentapplication is also related to U.S. patent application Ser. Nos.13/071,239, 13/071,198; 13/071,183; and 13/071,162; each filed on thesame day as the present application. The present application is alsorelated to U.S. Provisional Patent Application Nos. 61/317,198;61/317,114; 61/317,121; and 61/317,130, each filed on Mar. 24, 2010.

BACKGROUND OF THE INVENTION

The present invention relates to the field of medical stents and, moreparticularly, for the treatment of lesions and other problems in or neara vessel bifurcation. A stent is an endoprosthesis scaffold or otherdevice that typically is intraluminally placed or implanted within avein, artery, or other tubular body organ for treating an occlusion,stenosis, aneurysm, collapse, dissection, or weakened, diseased, orabnormally dilated vessel or vessel wall, by expanding the vessel or byreinforcing the vessel wall. In particular, stents are quite commonlyimplanted into the coronary, cardiac, pulmonary, neurovascular,peripheral vascular, renal, gastrointestinal and reproductive systems,and have been successfully implanted in the urinary tract, the bileduct, the esophagus, the tracheo-bronchial tree and the brain, toreinforce these body organs. Two important current widespreadapplications for stents are for improving angioplasty results bypreventing elastic recoil and remodeling of the vessel wall and fortreating dissections in blood vessel walls caused by balloon angioplastyof coronary arteries, as well as peripheral arteries, by pressingtogether the intimal flaps in the lumen at the site of the dissection.Conventional stents have been used for treating more complex vascularproblems, such as lesions at or near bifurcation points in the vascularsystem, where a secondary artery branches out of a typically larger,main artery, with limited success rates.

Conventional stent technology is relatively well developed. Conventionalstent designs typically feature a straight tubular, single type cellularstructure, configuration, or pattern that is repetitive throughtranslation along the longitudinal axis. In many stent designs, therepeating structure, configuration, or pattern has strut and connectingballoon catheter portions that impede blood flow at bifurcations.

Furthermore, the configuration of struts and connecting balloon catheterportions may obstruct the use of post-operative devices to treat adaughter vessel in the region of a vessel bifurcation. For example,deployment of a first stent in the mother lumen may prevent a physicianfrom inserting a daughter stent through the ostium of a daughter vesselof a vessel bifurcation in cases where treatment of the mother vessel issuboptimal because of displaced diseased tissue (for example, due toplaque shifting or “snow plowing”), occlusion, vessel spasm, dissectionwith or without intimal flaps, thrombosis, embolism, and/or othervascular diseases.

A regular stent is designed in view of conflicting considerations ofcoverage versus access. For example, to promote coverage, the cellstructure size of the stent may be minimized for optimally supporting avessel wall, thereby preventing or reducing tissue prolapse. To promoteaccess, the cell size may be maximized for providing accessibility ofblood flow and of a potentially future implanted daughter stent todaughter vessels, thereby preventing “stent jailing,” and minimizing theamount of implanted material. Regular stent design has typicallycompromised one consideration for the other in an attempt to addressboth. Problems the present inventors observed involving daughterjailing, fear of plaque shifting, total occlusion, and difficulty of theprocedure are continuing to drive the present inventors' into thedevelopment of novel, delivery systems, which are easier, safer, andmore reliable to use for treating the above-indicated variety ofvascular disorders.

Although conventional stents are routinely used in clinical procedures,clinical data shows that these stents are not capable of completelypreventing in-stent restenosis (ISR) or restenosis caused by intimalhyperplasia. In-stent restenosis is the reoccurrence of the narrowing orblockage of an artery in the area covered by the stent following stentimplantation. Patients treated with coronary stents can suffer fromin-stent restenosis.

Many pharmacological attempts have been made to reduce the amount ofrestenosis caused by intimal hyperplasia. Many of these attempts havedealt with the systemic delivery of drugs via oral or intravascularintroduction. However, success with the systemic approach has beenlimited.

Systemic delivery of drugs is inherently limited since it is difficultto achieve constant drug delivery to the afflicted region and sincesystemically administered drugs often cycle through concentration peaksand valleys, resulting in time periods of toxicity and ineffectiveness.Therefore, to be effective, anti-restenosis drugs should be delivered ina localized manner.

One approach for localized drug delivery utilizes stents as deliveryvehicles. For example, stents seeded with transfected endothelial cellsexpressing bacterial beta-galactosidase or human tissue-type plasminogenactivator were utilized as therapeutic protein delivery vehicles. See,e.g., Dichek, D. A. et al., “Seeding of Intravascular Stents WithGenetically Engineered Endothelial Cells,” Circulation, 80:1347-1353(1989).

U.S. Pat. No. 5,679,400, International Patent Application WO 91/12779,entitled “Intraluminal Drug Eluting Prosthesis,” and InternationalPatent Application WO 90/13332, entitled “Stent With Sustained DrugDelivery” disclose stent devices capable of delivering antiplateletagents, anticoagulant agents, antimigratory agents, antimetabolicagents, and other anti-restenosis drugs.

U.S. Pat. Nos. 6,273,913, 6,383,215, 6,258,121, 6,231,600, 5,837,008,5,824,048, 5,679,400 and 5,609,629 teach stents coated with variouspharmaceutical agents such as Rapamycin, 17-beta-estradiol, Taxol andDexamethasone. This and all other referenced patents are incorporatedherein by reference in their entirety. Furthermore, where a definitionor use of a term in a reference, which is incorporated by referenceherein is inconsistent or contrary to the definition of that termprovided herein, the definition of that term provided herein applies andthe definition of that term in the reference does not apply.

BRIEF SUMMARY OF THE INVENTION

The present invention relates to delivery catheters for delivery ofstents for placement at vessel bifurcations and is generally configuredto at least partially cover a portion of a daughter vessel as well as amother vessel. The invention comprises stent crimping methods todifferentially crimp a stent to account for stent design elements suchas a tapered stent that does not have uniform walls. Additionally,differential crimping can be applied to stents that are mounted on twocatheters.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, withreference to the accompanying drawings. With specific reference now tothe drawings, it is stressed that the particulars shown are by way ofexample and for purposes of illustrative discussion of the preferredembodiments of the present invention only, and are presented to providewhat is believed to be the most useful and readily understooddescription of the principles and conceptual aspects of the invention.In this regard, no attempt is made to show structural details of theinvention in more detail than is necessary for a fundamentalunderstanding of the invention, the description taken with the drawingsmaking apparent to those skilled in the art how the invention may beembodied in practice. In the drawings:

FIG. 1 is a cross sectional view of one embodiment with the mothercatheter an over the wire design and the daughter catheter with a rapidexchange.

FIG. 2 is a cross sectional view of one embodiment with the daughtercatheter an over the wire design and the mother catheter with a rapidexchange.

FIG. 3 is a cross sectional view of one embodiment with both mother anddaughter catheters with rapid exchange design.

FIG. 4 is a cross sectional view of one embodiment with both mother anddaughter catheters with an over the wire design.

FIG. 5 is a cross sectional view of one embodiment with the mothercatheter an over the wire design, the daughter catheter with a rapidexchange, and a capture tube.

FIG. 6 is a cross sectional view of one embodiment with the daughtercatheter an over the wire design, the mother catheter with a rapidexchange, and a capture tube.

FIG. 7 is a cross sectional view of one embodiment with both mother anddaughter catheters with rapid exchange design, and a capture tube.

FIG. 8 is a cross sectional view of one embodiment with both mother anddaughter catheters with an over the wire design, and a capture tube.

FIG. 9 is a cross sectional view of one embodiment with the mothercatheter an over the wire design, the daughter catheter with a rapidexchange, and a removable capture tube.

FIG. 10 is a cross sectional view of one embodiment with the daughtercatheter an over the wire design, the mother catheter with a rapidexchange, and a removable capture tube.

FIG. 11 is a cross sectional view of one embodiment with both mother anddaughter catheters with rapid exchange design, and a capture tube.

FIG. 12 is a cross sectional view of one embodiment with both mother anddaughter catheters with an over the wire design, and a capture tube.

FIG. 13 is a cross sectional view of one embodiment with the mothercatheter an over the wire design, the daughter catheter with a rapidexchange, and a short zipper.

FIG. 14 is a cross sectional view of one embodiment with the daughtercatheter an over the wire design, the mother catheter with a rapidexchange, and a short zipper.

FIG. 15 is a cross sectional view of one embodiment with both mother anddaughter catheters with rapid exchange design, and a short zipper.

FIG. 16 is a cross sectional view of one embodiment with both mother anddaughter catheters with an over the wire design, and a short zipper.

FIG. 17 is a cross sectional view of one embodiment with the mothercatheter an over the wire design and the daughter catheter with a rapidexchange, and an end to end zipper.

FIG. 18 is a cross sectional view of one embodiment with the daughtercatheter an over the wire design, the mother catheter with a rapidexchange, and an end to end zipper.

FIG. 19 is a cross sectional view of one embodiment with both mother anddaughter catheters with rapid exchange design, and an end to end zipper.

FIG. 20 is a cross sectional view of one embodiment with both mother anddaughter catheters with an over the wire design, and an end to endzipper.

FIG. 21 is a cross sectional view of one embodiment with the mothercatheter an over the wire design and the daughter catheter with a rapidexchange with a commercially available catheter.

FIG. 22 is a cross sectional view of one embodiment with the daughtercatheter an over the wire design and the mother catheter with a rapidexchange with a commercially available catheter.

FIG. 23 is a cross sectional view of one embodiment with both mother anddaughter catheters with rapid exchange design with a commerciallyavailable catheter.

FIG. 24 is a cross sectional view of one embodiment with both mother anddaughter catheters with an over the wire design with a commerciallyavailable catheter.

FIGS. 25-30 illustrate the delivery sequence of a preferred embodimentin eight steps.

FIG. 31 is a photograph of a preferred embodiment with a bifurcationstent partially crimped.

FIG. 32 is a photograph of a preferred embodiment with a bifurcationstent partially crimped with a second catheter threaded through thebifurcation stent hole.

FIG. 33 is a photograph of a preferred embodiment with a bifurcationstent partially crimped with a second catheter threaded through thebifurcation stent hole.

FIG. 34 is a photograph of a preferred embodiment with the system fullyaligned and fully crimped.

FIG. 35 is a cross sectional view of a differentially crimped stent ontwo catheters.

FIG. 36 is a profile view of a stent mounted on two balloon catheters.

FIG. 37 is a profile view of a stent mounted on two balloon catheters.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to delivery catheters for delivery ofstents for placement at vessel bifurcations and is generally configuredto at least partially cover a portion of a daughter vessel as well as amother vessel. In particular, the present invention relates to novelmethods of crimping stents to delivery catheters.

A variety of catheter designs may be employed to deploy and position themother and daughter stents. Such catheters may be used in connectionwith multiple guidewires that terminate in the mother and daughtervessels. These guidewires may be used to facilitate introduction of thecatheter, any angioplasty balloons, any stents, and/or to properlyorient the stent or balloon within the vessel.

In general, the methods of the invention may utilize a catheter systemcomprising a catheter body having a mother vessel guidewire lumen and adaughter vessel balloon that is independently operable and coupled tothe catheter body. The daughter balloon catheter portion has a daughtervessel guidewire lumen. The catheter system further includes mothercatheter balloon, and a stent is disposed over the balloon. The daughtercatheter portion extends into the proximal opening of the mother stentand exits the mother stent through a side passage of the mother stent.

According to one method, a mother vessel guidewire is inserted into themother vessel until a distal end of the mother vessel guidewire passesbeyond the ostium of the daughter vessel, and a daughter vesselguidewire is inserted into the mother vessel until a distal end of thedaughter vessel guidewire passes into the daughter vessel. To preventthe crossing of guidewires, the two vessels are wired through aguidewire catheter with two lumens to keep the guidewires separate anduntangled. This guidewire catheter is then removed and a wire separatoris placed on the wires to keep the guidewires unwrapped. The cathetersystem is then advanced over the mother and daughter vessel guidewires,with the mother and daughter vessel catheters passing over the mothervessel guidewire and the daughter vessel guidewire. The catheter systemis advanced on both wires with the daughter vessel balloon catheterportion distal to the mother balloon catheter portion. As the cathetersystem advances over the wires, the daughter vessel balloon will enterthe daughter vessel and may be deployed immediately or simultaneouslywith the mother vessel balloon after placement of the mother vesselballoon. The mother balloon catheter portion of the catheter system isthen advanced distally as far as it can be advanced to the bifurcationsite because the tension of the daughter catheter on the mother stentwill prevent the mother catheter from moving distally. This methodfacilitates advancement of the catheter system to the bifurcation, whichmay be necessary for tortuous or calcified coronaries. Once the cathetersystem is in place the daughter vessel balloon catheter portion is thenpulled back relative to the mother catheter so that it is partiallywithin the mother stent, alignment can be performed with radiopaquemarkers. The operator can then gently push the catheter system distal tomaximize apposition to the carina. The daughter balloon is then inflatedto ensure proper alignment of the mother stent. The daughter balloon mayalso have a stent on its distal portion, which would result in theproximal portion of the mother stent and the daughter stent to expandsimultaneously. The daughter balloon is then deflated. The motherballoon is then inflated which deploys the mother stent. Kissing,reinflation, of the two balloons is done if necessary or for shiftingplaque. The catheter system may be removed while the wires remain inplace. The daughter vessel can be stented if necessary with anycommercially available stent for example a short stent that would notcover the entire daughter balloon. The two vessels may be angioplastiedseparately as necessary predilatation is indicated on occasion.

In an alternative method, the mother catheter can be mounted on thedaughter vessel guidewire and the daughter catheter can be mounted onthe mother vessel guidewire. In daughter vessels with a high degree ofangularity, over 60-70%, the friction is lower when the operator needsto draw the daughter stent proximal and into the mother stent in thisconfiguration. The catheter system is advanced so the daughter ballooncatheter can pass the ostium of the daughter vessel and remain in themother vessel. As the catheter system is advanced further, the motherballoon catheter will enter the daughter vessel. The catheter system canonly be advanced to the bifurcation because there is tension between thedaughter catheter in the mother vessel and mother stent on the mothercatheter that prevents further advancement. While the mother catheter isheld in place, the daughter catheter is drawn back such that theproximal portion of the daughter balloon is in the mother stent.Alignment is performed with radiopaque markers. The operator can thengently push the catheter system distal to maximize apposition to thecarina. A stent on the daughter balloon is aligned so that when thedaughter balloon is inflated the daughter stent and the proximal portionof the mother stent expand simultaneously and give complete coverage ofthe mother vessel. The daughter vessel balloon is then deflated. Themother vessel balloon is then inflated and the distal portion of themother stent is expanded. A kissing procedure can also be performed ifrequired.

In an alternative embodiment, the system can be used for provisionalstenting of the daughter vessel. The catheter system comprising mothercatheter comprising a mother balloon and mother stent, and a daughtercatheter comprising a daughter balloon wherein the mother catheter isloaded onto a daughter vessel guidewire and the daughter catheter isloaded onto the mother vessel guidewire. The catheter system is advancedso the daughter balloon catheter can pass the ostium of the daughtervessel and remain in the mother vessel. As the catheter system isadvanced further, the mother catheter and mother stent will enter thedaughter vessel. The catheter system can only be advanced to thebifurcation because there is tension between the daughter catheter inthe mother vessel and mother stent on the mother catheter that preventsfurther advancement. While the mother catheter is held in place, thedaughter catheter is drawn back such that the proximal portion of thedaughter balloon is in the mother stent. Alignment is performed withradiopaque markers. The operator can then gently push the cathetersystem distal to maximize apposition to the carina. A balloon on a wirecould be used as an alternative to the daughter catheter.

In an alternative embodiment, the system can be used for provisionalstenting of the daughter vessel. The catheter system comprising; amother catheter comprising a mother balloon and, a daughter cathetercomprising a daughter balloon and a daughter stent on the distal portionof the daughter balloon wherein the mother catheter is loaded onto amother vessel guidewire and the daughter catheter is loaded onto thedaughter vessel guidewire. The catheter system is advanced on both wireswith the daughter balloon catheter portion distal to the mother ballooncatheter portion. As the catheter system advances over the wires, thedaughter balloon will enter the daughter vessel. The mother ballooncatheter portion of the catheter system is then advanced distally as faras it can be advanced to the bifurcation. Once the catheter system is inplace the daughter vessel balloon catheter portion is then pulled backrelative to the mother catheter so that it is partially within themother vessel, alignment can be performed with radiopaque markers. Theoperator can then gently push the catheter system distal to maximizeapposition to the carina. The daughter balloon and mother balloon aresimultaneously inflated. The mother vessel can be stented if necessarywith any commercially available stent. A balloon on a wire could be usedas an alternative to the daughter catheter.

In an alternative embodiment, the catheter system can be arranged withthe daughter balloon portion proximal to the mother balloon portionforward over the guidewires to the bifurcation. In the case of themother catheter on the mother guidewire, the alignment of the motherstent with the ostium of the daughter vessel occurs because tensionbetween the daughter guidewire and mother stent on the mother catheterthat prevents further advancement of the mother catheter. In thealternative case of the mother catheter on the daughter guidewire, thealignment of the mother stent with the ostium of the mother vesseloccurs because tension between the mother guidewire and mother stent onthe mother catheter that prevents further advancement of the mothercatheter. In both cases the daughter stent is advanced distally intoalignment with the mother stent and expanded.

In preferred embodiments, FIGS. 1 and 4 show the mother catheter is anOver-the-Wire (OTW) design and the daughter catheter is a Rapid-Exchange(RX) design with daughter catheter portion about 3 centimeters distalthe mother catheter portion. The daughter balloon is placed just distalto the tip of the mother catheter, this arrangement minimizes theoverall profile of the catheter system and allows maximal tracking ofthe arteries. The system may additionally have stents crimped over theballoons. The daughter stent may be approximately half the length of thedaughter balloon or mother stent. The proximal end of the mother stentmay be crimped only slightly to allow the daughter catheter balloonportion to operate independently, i.e. may be pushed or pulled withoutdislodging the mother stent. The method comprising the following steps:

1. Advance the catheter system to bifurcation, daughter balloon catheterportion and mother balloon catheter portion in their respective vessels.The mother catheter is no longer able to advance because of the tensionbetween the mother stent and daughter catheter.

2. The daughter balloon proximal portion is drawn back into the motherstent and aligned with radiopaque markers.

3. While holding both the mother and daughter catheters tightly, theoperator pushes forward lightly.

4. Inflate the daughter balloon and expand the daughter stent,approximately half of the daughter balloon distal portion will expandthe “half-stent,” and half of the daughter balloon proximal portion willexpand inside the mother vessel and partially expand the proximalportion of the mother stent.

5. Once the daughter stent is fully deployed, then the mother ballooncan be fully expanded to deploy the distal portion of the mother stent.

6. A conventional Kissing procedure may be utilized to ensure fullapposition.

In one particular aspect, the daughter balloon catheter portion may beused without a stent. This would allow perfect alignment of mother stentaround the ostium of the daughter vessel. The daughter balloon would beused for the alignment as outlined in step three above, and expand theproximal portion of the mother stent.

In an alternative embodiment, FIG. 5 shows the mother catheter is anOver-the-Wire (OTW) design and the daughter catheter is a Rapid-Exchange(RX) design with daughter catheter balloon portion about 3 centimetersdistal the mother catheter balloon portion. The system may additionallyhave stents crimped over the balloons. The daughter stent may beapproximately half the length of the mother balloon or stent. Theproximal end of the mother stent may be crimped only slightly to allowthe daughter catheter balloon portion to operate independently, so thatit may be pushed or pulled without dislodging the mother stent. Themethod comprising the following steps:

1. Looping the OTW so that one operator can hold both guide wires withone hand and then push both catheters with the other.

2. Advance the catheter system to bifurcation, daughter balloon catheterportion and mother balloon catheter portion aligned in their respectivevessels, as disclosed in steps two through three in the aboveembodiment.

3. While holding both the mother and daughter catheters tightly, pushthe catheter system forward until the mother balloon catheter portion isstopped at the carina.

4. Inflate the daughter balloon and expand the daughter stent,approximately half of the daughter balloon distal portion will expandthe “half-stent,” and half of the daughter balloon proximal portion willexpand inside the mother vessel and partially expand the proximalportion of the mother stent.

5. Once the daughter stent is fully deployed, then the mother ballooncan be fully expanded to deploy the distal portion of the mother stent.

6. A conventional Kissing procedure may be utilized to ensure fullapposition.

In one particular aspect, the daughter balloon catheter portion may beused without a stent. This would allow perfect alignment of mother stentaround the ostium of the daughter vessel. The daughter balloon would beused for the alignment as outlined in step three above, and expand theproximal portion of the mother stent.

In an alternative embodiment, the mother catheter is an Over-the-Wiredesign and the daughter catheter is a Rapid-Exchange design withdaughter catheter portion about 3 centimeters distal. The system mayadditionally have stents crimped over the balloons. The daughter stentmay be approximately half the length of the mother balloon or stent. Theproximal end of the mother stent may be crimped only slightly to allowthe daughter catheter balloon portion to operate independently, i.e. maybe pushed or pulled without dislodging the mother stent. The methodcomprising the following steps:

1. Place the daughter guidewire only and then slide the system into theguide catheter. Just before exiting the guide catheter, insert themother guide wire through the catheter and into the mother vessel, thenpush the system out of the guide catheter. To reduce wire wrap.

2. Advance the catheter system to the bifurcation, daughter ballooncatheter portion and mother balloon catheter portion aligned in theirrespective vessels.

3. Advance the catheter system to bifurcation, daughter balloon catheterportion and mother balloon catheter portion aligned in their respectivevessels, as disclosed in step two in the above embodiment.

4. Inflate the daughter balloon and expand the daughter stent,approximately half of the daughter balloon distal portion will expandthe “half-stent,” and half of the daughter balloon proximal portion willexpand inside the mother vessel and partially expand the proximalportion of the mother stent.

5. Once the daughter stent is fully deployed, then the mother ballooncan be fully expanded to deploy the distal portion of the mother stent.

6. A conventional Kissing procedure may be utilized to ensure fullapposition.

In one particular aspect, the daughter balloon catheter portion may beused without a stent. This would allow perfect alignment of mother stentaround the ostium of the daughter vessel. The daughter balloon would beused for the alignment as outlined in step three above, and expand theproximal portion of the mother stent.

In an alternative embodiment the mother and daughter systems balloonsare aligned. This embodiment could include the mother stent and daughterstent or either stent. When there is both a mother stent and a daughterstent, the daughter stent would be approximately half the length of themother stent so that the daughter stent could be mounted on the distalhalf of the daughter balloon. Further the proximal portion of thedaughter catheter would be crimped under the mother stent. The dualstent arrangement would reduce the profile compared to a full lengthstent that covered the entire length of the daughter balloon.

The methods described herein could alternatively include the step offlushing the catheters and the guidewire port to assist withmaneuverability. The methods described herein could alternativelyinclude the step of a couple of snap-on couplers the catheters arelocked together.

In another particular aspect, each balloon catheter portion may includeat least one radiopaque marker. With such a configuration, separation ofthe markers may be conveniently observed using fluoroscopy to indicatethat the balloon catheter portions have passed beyond the ostium and thedaughter balloon catheter portion has passed into the daughter vessel,thus aligning the passage of the stent with the ostium of the daughtervessel.

In another particular aspect, the catheter systems design iscontemplated to cover combinations of rapid exchange and over the wire;for visualization purposes the hybrid versions are preferred becausethey are easier to distinguish while using fluoroscopy.

In another particular aspect, the proximal balloon may be differentiallyexpandable, such that one end of the balloon may expand prior to theother end. In another particular aspect, the proximal balloon catheterportion may receive a stent that can be crimped under variable pressureto allow the distal balloon catheter portion freedom of movement.

In another particular aspect, a stent may be crimped over the proximalballoon catheter portion and the stent may be designed to deploy withvariable profile to better oppose the patient anatomy.

In another particular aspect, the distal balloon catheter portion may bedelivered via a pull away.

All of the above embodiments may utilize mother vessel stents rangingfrom 2.5 to 5.0 millimeter in diameter and daughter vessel stent rangingfrom 2.0 to 5.0 millimeter in diameter. The length of the stents couldbe in the range of 4 to 40 millimeter. The position of a stent on acatheter is not fixed and can be positioned on either or both catheters.

FIG. 1 illustrates the catheter system 10 with a distal daughter ballooncatheter portion 30 comprising a balloon 32 with a daughter stent 33crimped (not shown). The daughter stent 33 may be shorter than themother stent 23. In a particular embodiment the daughter stent 33 ishalf the length of the mother stent 23 (not shown). The distal daughterstent 33 is crimped under standard conditions known in the art. Theproximal mother balloon catheter portion 20 comprises a mother balloon22 and a mother stent 23. The mother stent 23 is crimped differentiallyalong the longitudinal direction and circumferentially, FIGS. 36-37. Inthe particular embodiment, the distal half 23 a of the mother stent 23is crimped under typical conditions to ensure that the mother stent 23is not dislodged during the alignment with the distal daughter balloon32. Further, the proximal portion 23 b of the mother stent 23 is crimpedunder non-standard, relatively loose, conditions to allow the distaldaughter balloon catheter portion 30 freedom of movement even though aportion of the daughter balloon catheter portion 30 is circumferentiallyenclosed. The mother catheter 21 and daughter catheter 31 are slidablyattached to each other via a hollow exchange port 40. The exchange port40 is embedded in the side of the mother over the wire catheter. Theexchange port 40 is 10 centimeters long with a diameter just largeenough to allow the insertion of the rapid exchange daughter catheterand daughter 31 balloon 32. The exchange port 40 can vary in length from1 centimeter to 30 centimeters. The entry for the daughter catheter 32on the exchange port 40 is proximal and the exit for the daughtercatheter 32 is on the distal end of the exchange port 40. The daughtercatheter 32 is loaded through the exchange port 40 and the daughterballoon 32 extends distally 5 centimeters from the exit of the exchangeport 40 5 centimeters. However, it is possible to have the exchange port40 1 to 30 centimeters proximal to the mother balloon 22. The motherstent 23 can be crimped on to the balloon after it has been loadedthrough the exchange port 40. The exchange port 40 must have a tight fitto reduce catheter profile and have low friction to allow the operatorto easily slide the catheters relative to each other.

FIG. 2 illustrates a cross sectional view of one embodiment with themother catheter balloon portion 20 proximal to the daughter catheterballoon portion 30 utilizing the same exchange port 40 as described inFIG. 1. The daughter balloon 32 is 5 centimeters distal from the exit ofthe exchange port 40. As disclosed above, the daughter balloon 32 couldbe distal from the exchange 40 port 1 to 30 centimeters.

FIG. 3 illustrates a cross sectional view of one embodiment with themother and daughter catheters both having a rapid exchange design. Inthis particular embodiment one of the catheters has an exchange port 40embedded in its side and the other catheter is loaded through theexchange port 40. Typically, the catheter would have to be loaded priorto having a stent crimped over the balloon portion.

FIG. 4 illustrates a cross sectional view of one embodiment with themother and daughter catheters both having an over the wire design. Inthis particular embodiment one of the catheters has an exchange port 40embedded in its side and the other catheter does not have an exchangeport. The catheter without the exchange port would be loaded onto thecatheter with an exchange port 40. Typically, the catheter would have tobe loaded prior to having a stent crimped over the balloon portion.

FIGS. 5-8 illustrate an end to end capture tube 41 that connects thecatheters together. FIGS. 5-6 The capture tube 41 is a thin polymerhollow straw that covers the mother and daughter catheters from a point10 centimeters distal the Indeflator® attachment 43 to a distal pointthat is 10 centimeters proximal from the rapid exchange catheter'sproximal rapid exchange port 47. FIG. 7 discloses dual rapid exchangemother and daughter catheters so the end point of the capture tube 41would be 10 centimeters proximal from the rapid exchange catheters'rapid exchange port 47 on the proximal catheter. FIG. 8 embodies acatheter system with dual over the wire designs, therefore the capturetube 41 ending point ends 30 centimeters proximal from the balloonportion of the most distal catheter. The capture tube 41 keeps thecatheters from tangling. The capture tube 41 remains in place during theentire clinical procedure. FIG. 6 illustrates a distal daughter catheter31 with an over the wire design and a proximal mother catheter 21 with arapid exchange design. FIG. 5 illustrates a proximal mother catheter 21with an over the wire design and a distal daughter catheter 31 with arapid exchange design.

FIGS. 9-12 illustrate a removable capture tube 42 that is fitted overthe dual catheters as described above but the capture tube 42 has apolymer appendage 44. Once the operator has the catheter system placednear the bifurcation the operator can grab hold of the polymer appendage44 and pull the capture tube 42 off of the catheters. FIG. 10illustrates a distal daughter catheter 31 with an over the wire designand a proximal mother catheter 21 with a rapid exchange design. FIG. 9illustrates a proximal mother catheter 21 with an over the wire designand a distal daughter catheter 31 with a rapid exchange design. FIG. 11illustrates a dual rapid exchange design with a removable capture tube42. FIG. 12 illustrates a dual over the wire design with a removablecapture tube 42.

FIGS. 13-16 illustrate a zipper 45 that allows one catheter to snap into the other catheter. The zipper 45 is essentially a groove that formsa concave receiving cross section and is carved into a catheter's outersurface in a straight line. The groove can be a single groove over acertain portion of a catheter or it can run from end to end.Alternatively, the catheter can have a series of short grooves of 1 to10 centimeters in length that run the length of the catheter or only acertain portion. Full length end to end zippers will have reducedprofile and reduced friction with the vessel. The resulting groove canreceive another catheter and prevent the catheters from dislodging whilethe operator is advancing the catheters to the bifurcation. Once at thesite the operator can still slidably move the catheters forward and backrelative to each other. Mother catheters that utilize the groove canhave fully crimped stents as described in several of the embodimentsabove; however, it is possible to allow operators to choose anycommercially available catheter with or without a stent and mount thecommercially available catheter via the zipper 45. The mother catheterswith an empty zipper 45 would have a mother stent 23 full crimped on thedistal balloon portion 22 a of the mother catheter 21. After loading thecommercially available catheter the operator would have to crimp theproximal portion of the mother stent 23 b in situ prior to beginning theclinical procedure. This option may be extremely valuable to operatorswho can reduce their total inventory of catheters but have more optionsfor treating bifurcated lesions. FIG. 14 illustrates a distal daughtercatheter 31 with an over the wire design and a proximal mother catheter21 with a rapid exchange design and a short zipper 45. FIG. 13illustrates a proximal mother catheter 21 with an over the wire designand a distal daughter catheter 31 with a short zipper 45. FIG. 15illustrates a dual rapid exchange design with a short zipper 45. FIG. 16illustrates a dual over the wire design with a short zipper 45. FIG. 18illustrates a distal daughter catheter 31 with an over the wire designand a proximal mother catheter 21 with a rapid exchange design and anend to end zipper 45. FIG. 17 illustrates a proximal mother catheter 21with an over the wire design and a distal daughter catheter 31 with anend to end zipper 45. FIG. 19 illustrates a dual rapid exchange designwith an end to end zipper 45. FIG. 20 illustrates a dual over the wiredesign with an end to end zipper 45.

FIGS. 21-24 illustrate commercially available catheters that can be usedwith an alternative embodiment where in the mother catheter 21 isprovided to the operator with a mother stent 23 (not shown) that iscrimped on the distal portion of the mother catheter balloon 22 a. Theproximal portion 23 b of the mother stent 23 is uncrimped. The operatorcan mount any commercially available catheter or balloon on a wirethrough the end of the mother stent proximal portion 23 b and exit outthe side hole 25 of the mother stent 23. See FIG. 36. The operator canalign the catheters to suit the patient's anatomy and crimp the proximalportion 23 b of the mother stent 23. The operator can crimp the stent 23tightly so that the catheters do not move relative to each other. It ispossible for the operator to place the catheters at the bifurcation andif necessary pullback on the commercially available catheter to adjustthe alignment if necessary. Then the operator can gently push the systemdistally to ensure complete apposition. FIG. 21 illustrates a distaldaughter catheter 31 with a rapid exchange design and a proximal mothercatheter 21 with an over the wire design. FIG. 22 illustrates a distaldaughter catheter 31 with an over the wire design and a proximal mothercatheter 21 with a rapid exchange design. FIG. 23 illustrates a dualrapid exchange design. FIG. 24 illustrates a dual over the wire design.

Alternative embodiments of commercially available catheters that aresingle use devices for treating a single vessel, but can be matedtogether in various combinations with a polymer sleeve. The operatorchooses the two catheters for the patient's anatomy then slides a sizedpolymer sleeve over both catheters from the distal ends. Once theoperator has the catheters aligned the polymer sleeve can be treatedwith a heat or light source to shrink and bond the two catheterstogether with friction. The polymer sleeve is made of typical polymersthat can act as shrink wrap when treated with a heat or light source.The polymer of the polymer sleeve for example could be manufactured withpolyolefin a chemical used in manufacturing shrink wrap. The polymersleeve would not crosslink or covalently attach to the catheters,several types of polymers are commercially available and have therequisite properties, thin, strong, not adhesive, and reaction times totheir source of ten minutes or less. The polymer sleeves are typically15 centimeters in length and have various diameters to suit typicalcatheter diameters 4 French to 20 French. The operator can test that thebond is holding by applying slight pressure prior to the procedure. Ifthe polymer sleeve does not hold tightly the operator may elect to use asmaller diameter polymer sleeve or use more than one polymer sleeve byplacing the polymer sleeves adjacent to each other. Alternatively,several smaller sleeves from 1 to 10 centimeters in length could beplaced over several different portions of the catheters.

FIGS. 25-30 illustrate the delivery sequence of a preferred embodimentin eight steps. Step 1 illustrates the introduction of a 0.035 inchguidewire 50 up to the bifurcation. Step 2 illustrates the tracking of aguide catheter 53 over the guidewire 50. Step 3 illustrates the removalof the guidewire 50 and placement position of the guide catheter 53.Step 4 illustrates the tracking and placement of a rapid exchangecompatible wire 52 in the daughter vessel 2 and an over the wirecompatible wire 51 in the mother vessel 1. Step 5A & 5B illustratetracking of the catheter system 10 distally over both the guidewires.Step 6A illustrates the inflation of the daughter balloon 32 andplacement of the daughter stent 33 and partial deployment of the motherstent 23. Step 6B illustrates the inflation of the mother balloon 22 toplace the distal portion 23 a of the mother stent 23 in the mothervessel 1. Step 7A illustrates the mother stent 23 in the main branchwith side hole 25 facing the daughter vessel 2. Step 7B illustrates abifurcated stent partially in the daughter vessel 2 and the mothervessel 1 where a side hole 25 of the mother stent 23 opens toward themain branch vessel 1.

In an alternative embodiment the delivery catheter mother balloonshaving tapered ends to accommodate balloons and stents with non-uniformprofiles. For example, the proximal end of the daughter vessel stent maybe designed to have a larger circumference than the distal end tocompensate for the natural bifurcation anatomy. The daughter vesselballoon would like wise have a taper to properly expand the stent andensure complete apposition. Additionally, it is possible to design themother stent to expand differentially along its profile to compensatefor a larger arterial diameter at the carina or ostium. In other words,the proximal and distal ends of the mother vessel balloon and mothervessel stent would be smaller in circumference while the center portionof the mother vessel stent would have a larger circumference.

In an alternative embodiment the mother vessel balloon having taperedends to accommodate the distal balloon catheter portion and guidewirelumen. Further, the mother vessel balloon is designed for differentialexpansion to accommodate natural vessel anatomy.

In a preferred embodiment wherein the distal (daughter) balloon catheterportion is crimped with a half stent on a rapid exchange type designcatheter. The daughter vessel stent is 4-20 millimeter and the daughtervessel balloon is approximately twice as long in length. The mothervessel stent 10-30 millimeter is differentially crimped to allowindependent operation of the daughter balloon catheter portion. Thedistal portion of the mother vessel stent is crimped tightly enough tokeep the entire stent from unintentionally dislodging during theprocedure. The proximal portion of the mother vessel stent is crimpedjust tightly enough to reduce the crossing profile and allow thedaughter balloon catheter portion to be moved distal or proximalrelative to the mother balloon catheter portion. The proximal (mother)balloon catheter portion is an over the wire type design with the mothervessel balloon about 3 centimeters proximal to the daughter vesselballoon.

In an alternative embodiment a stent is designed to allow differentialexpansion of the middle portion of the stent relative to the proximaland distal ends. In particular, the design facilitates the placement ofthe stent across a bifurcation lesion in the mother vessel because ithas a larger circumference in the middle portion relative to the endsthan a stent with a constant profile. Further, the profile can beadjusted so that the largest circumference can be placed proximal ordistal to the midpoint of the stent. In the particular embodiment thelargest circumference is distal to the midpoint of the stent, but couldbe easily reversed for variable patient anatomy.

Partial crimping has the following key features that make it possible tomaintain sufficient stent retention during delivery and placement andstill allows the secondary system adjustability and deliverability. FIG.31 is a partially crimped bifurcation stent prior to placement on anyballoon catheter. FIGS. 32-34 illustrate an embodiment of the presentinvention in three steps. First, the bifurcation stent 23 is partiallycrimped over approximately one-third the distal portion 23 a of thebifurcation stent on to the mother catheter 21 and the daughter catheter31 is loaded through the mother catheter 21 and mother stent 23 wherethe daughter stent 33 can be crimped separately. Second, the daughterstent 33 is crimped and pulled back proximally to align the proximal endof the daughter stent 33 near the distal end of the mother stent 23.Third, the proximal portion of the mother stent 23 b can be crimped toreduce the outer diameter, yet still allow independent movement of thetwo catheters relative to each other.

FIG. 35 illustrates a cross section of a daughter balloon catheter 31without a daughter stent. The daughter catheter 31 is on top of themother catheter 21. The mother stent 23 is differentially crimped aroundthe mother catheter balloon 22 and daughter catheter 31 because thedaughter catheter 31 profile is smaller than the mother catheter 21profile. The differential crimping is non-uniform and can create variouscross sectional shapes to accommodate different catheter designs,balloon designs, and stent designs. For example, pear shaped or a figureeight are possible configurations. The current embodiment is designed toreduce the profile as much as possible. In one preferred method ofmanufacturing, a protective sheet 46 is placed between the twocatheters. The protective sheet 46 only needs to cover the portions thatwill come in contact during the crimping process, then the protectivesheet 46 can be removed. FIG. 36 illustrates a side view of the motherstent 23 mounted on the mother catheter balloon 22 and the daughtercatheter 31 mounted on the mother catheter 21 through the mother stent22. The distal portion 23 a of the mother stent 23 will be crimped understandard conditions to hold stent firmly to the mother balloon 22 andmother catheter 21. The proximal portion 23 b of the mother stent 23 ispartially crimped to reduce the profile, but still allows the daughtercatheter 31 freedom to move proximal or distal relative to the mothercatheter 21. This embodiment illustrates that the stent 23 isdifferentially crimped in both the circumferential and longitudinaldirection. The amount of crimping will be determined by the stent designand size, catheter dimensions, and balloon dimensions; thus the crimpingis differential along the longitudinal axis. FIG. 37 illustrates a sideview of the mother stent 23 mounted on the mother catheter balloon 22and the daughter catheter 31 mounted on the mother catheter 21 throughthe mother stent 23. The daughter catheter 31 also includes a stent 33that can be crimped under standard conditions. The distal portion 23 aof the mother stent 23 will be crimped under standard conditions to holdstent firmly to the mother balloon 22 and mother catheter 21. In oneexperiment, this arrangement was tested to determine the strength of thedistal crimping of the mother stent 23 by pulling the daughter catheter31 and daughter stent 33 proximally; the results were that the daughtercatheter 31 successfully passed through the crimped mother stent 23 andstill retained the daughter stent 33 as well.

Additional features may be utilized during the crimping process such asadding a slight positive internal pressure to the balloon so that thefinal balloon surface pillows about 0.002 inch beyond the outer diameterof the stent. This process can yield a design that protects the stentfrom engaging with the vessel thus reducing friction and improving stentretention at the same time. Further, this process improves safety andreduces trauma to the vessel.

While the above embodiment discloses a bifurcation stent that is crimpedat or about its distal half; this is not a limitation. The stent couldbe differentially crimped along its axis depending upon stent design,for example; if a hole in the side of a stent was not centered along theaxis. It may be preferential to have the distal crimped portion of thebifurcation stent extend just distal of the hole that the daughtercatheter to pass through. Alternatively, the distal crimped portioncould extend partially or entirely over the hole that the daughtercatheter passes through.

While the invention has been described in conjunction with specificembodiments and examples thereof, it is evident that many alternatives,modifications and variations will be apparent to those skilled in theart upon reading the present disclosure. Accordingly, it is intended toembrace all such alternatives, modifications and variations that fallwithin the spirit and broad scope of the appended claims.

What is claimed is:
 1. A method for treating a bifurcated vessel havinga mother vessel and a daughter vessel, said method comprising: providinga catheter system for delivery of a stent at the bifurcated vessel, thecatheter system comprising: a mother catheter having a mother expandablemember with a mother stent disposed thereon, the mother stent having aside hole for alignment with an ostium of the daughter vessel, whereinthe mother stent has a crimped configuration for delivery through avessel and an expanded configuration in which the stent supports avessel wall of the mother or daughter vessel; and a daughter catheterhaving a daughter expandable member, the daughter catheter extendingthrough the side hole of the mother stent in the crimped configuration;advancing the catheter system through the mother vessel having thebifurcated vessel with the daughter expandable member distal of andadvanced concurrently with the mother expandable member, while themother stent is in the crimped configuration; advancing the daughterexpandable member into the daughter vessel; advancing the mothercatheter through the mother vessel until the mother stent is positionedat the bifurcated vessel and the side hole is adjacent the ostium of thedaughter vessel; proximally retracting the daughter catheter relative tothe mother catheter so that the daughter expandable member is partiallywithin the mother stent, and so that a proximal end of the daughterexpandable member is proximal of a proximal end of the mother stent anda distal portion of the daughter expandable member is within thedaughter vessel, while the mother stent is in the crimped configuration;expanding the daughter expandable member so as to align the side holewith the ostium of the daughter vessel, wherein expanding the daughterexpandable member expands a proximal portion of the mother stent fromthe crimped configuration.
 2. The method of claim 1, further comprising:expanding the mother expandable member to fully expand the mother stentinto the expanded configuration after expansion of the proximal portionof the mother stent from the crimped configuration by the expansion ofthe daughter expandable member.
 3. The method of claim 1, whereinadvancing the mother catheter comprises advancing the mother catheterdistally until tension of the daughter catheter on the mother stentprevents the mother catheter from moving further distally.
 4. The methodof claim 1, wherein advancing the mother catheter comprises advancingboth the mother and daughter catheters until resistance to furtheradvancement is felt by an operator.
 5. The method of claim 1, whereineach of the mother and daughter catheter comprises at least oneradiopaque marker observable with fluoroscopy, and wherein retractingthe daughter catheter comprises retracting the daughter catheter untilthe at least one radiopaque marker of the daughter catheter is alignedwith the at least one radiopaque marker of the mother catheter so as toindicate when the daughter expandable member is sufficiently retractedwithin the mother stent.
 6. The method of claim 1, wherein the motherand daughter catheters are slidably coupled to each other with anexchange tube to prevent tangling of the catheters during delivery. 7.The method of claim 6, wherein the exchange tube is attached to a sideof the mother catheter, and wherein retracting the daughter cathetercomprises retracting the daughter catheter through the exchange tube. 8.The method of claim 1, wherein one of the mother catheter and daughtercatheter comprises an exchange tube embedded in a side of the catheterthrough which the other catheter is slidably attached.
 9. The method ofclaim 1, wherein the daughter catheter further comprises a daughterstent disposed on the daughter expandable member, the daughter stenthaving a crimped configuration for delivery through a vessel and anexpanded configuration in which the stent supports a vessel wall of themother or daughter vessel, and wherein expanding the daughter expandablemember expands the daughter stent into the expanded configuration. 10.The method of claim 9, wherein expanding the daughter expandable memberconcurrently expands at least the proximal portion of the mother stentfrom the crimped configuration and the daughter stent.
 11. The method ofclaim 10, further comprising: expanding the mother expandable member tofully expand the mother stent into the expanded configuration afterexpansion of the daughter expandable member.
 12. The method of claim 11,wherein the daughter expandable member is contracted before expandingthe mother expandable member.
 13. The method of claim 11, wherein thedaughter expandable member and the mother expandable member are expandedconcurrently so as to kiss one another to ensure proper alignment of theside hole with the ostium of the daughter vessel and expansion of themother stent at the bifurcation.
 14. The method of claim 11, wherein thedaughter expandable member and the mother expandable member arere-expanded concurrently after each of the daughter and motherexpandable members have been expanded and contracted.